Improvement in telegraphs



l A. BAIN'. ELECTROv ACOUSTIC TBLBGRAPH. No. 32,854. Patented July 23, 1861.`

' lll UNITED STATES PATENT OFFICE.

ALEXANDER BAIN, OF NEW YORK, N. Y.

IMPROVEMENT IN TELEGRAPHS.

Specification forming partof Letters Patent No. 32,854, dated July 23, 1861.

To all whom. 'it may concern:

Be itknown that I, ALEXANDER BAIN, of the city, county, and State of New York, have invented a new and useful Improvement in Electric Telegraphs, and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this speciiication.-

The advantages sought to be obtained by this invention, which I denominate the electro-acoustic telegraph, are, iirst,the inviolable secrecy of all important telegraphic communications, and, second, the saving of expense in the working of telegraph-lines.

It is a common practice in telegraph-edities to read and write down the messages from the sound or click lof the magnets, and with the 'apparatus ordinarily used the sound can fre'- qnently be heard in all parts of an oftice, and even outside, with such distinctness that the messages may be understood not only by the confidential clerk whose duty it is to write them down and send them inviolate to the person or persons for whom they are intended, but by other persons of quickear familiar with the telcgrapnic alphabet, who may be by accident or design in or near the same oiiice or 1 in or near other ofiices whose magnets are in the same circuit, and consequently are similarly acted upon to the magnet in the office for which the message was intended.

To obviate this objection my invention consists in so applying an acoustic tube, in combination with the lever carrying the armature of a magnet, or with any other instrument for producing sounds by electricity, that a person having the tube applied to his ear may hear the sound while it is inaudible to persons at a very short distance from the instrument.

It also consists in the employment, in combination with a so-applied acoustic tube, of a cover of glass or other material inclosing the instrument for the purpose of preventing the sound escaping in any great degree except by the acoustic tube, and of aiding to convey the sound into the said tube. The saving of expense results from so,little sound being required when all is conveyed to a point where alone it is wanted-viz., the ear of the operator-that the long-circuit magnets will serve .Fig. 2 is a section of the ear-tube.

every purpose without the use of local magnets, circuits, or batteries, though these, of course", may be used, if desirable, to apply my invention in connection with any of the present modes of operating.

The accompanying drawings represent an instrument in what I consider the best torm for applying my invention to use.

i Figure lisa vertical section of the instrument, showing the application of the ear-tube. Figisa plan of the instrument without the cover. Fig. 4 represents the alphabet of signs which l propose to employ. c

Similar letters ot' reference indicate corresponding parts in the several figures.

A is a wooden stand, of circular or other convenient form, having a rim, a a, all round it, and having its upper surface within this rim covered with a circular sheet or disk, B, of

elastic india-rubber.

C is a smaller wooden stand, of `form corresponding with A, resting on the india-rubber B, and secured firmly to the stand A by screws b b, which keep the india-rubber firmly in place.

D D is an electro-magnet, secured in the usual way to the stand O.

E is the armature of the said magnet, attached firmly to a lever, F, which is secured to a small horizontal shaft, d., that is arranged to oscillate between two center screws, e e,

e screwing into lugs at opposite ends of a plate,

G, which is secured firmly to the stand O. The said lever F has a hammer-like upper extremity, as shown at n in Fig. 1, and has attached rigidly to it a hooked arm, f, with -which is connected the upper end of a spiral spring, g,

the lower part ot' which is received in a pit, h, provided for it in the stands C and A. rEhe lower extremity of this spring is attached to the upper end of a silk cord, i, the lower end of which is attached to a horizontal spindle, H, which crosses the lower part of the pit h, the said spindle being received in a hole bored through one side of the stan( Ato meet the pit h, and the inner bearingo the said spindle being in a hole, j, bored on one side of the pit h,and the outer bearingof the said spindle being in a piece of elastic india-rubber, k, which is secured by a plate of brass, l, and

- screws m m to the outside of stand A.

The outer end ofthe spindle H is furnished with a knob, n, by which to turn it to wind up or unwind the cord t', for the purpose of4 producing more or lesstension on the spring g, which exerts a tendency to draw back the armaturedever F and pull the armature away from the poles of the magnet. 'lheindia-rub-4 ber 7c is so clamped' around the spindle by the plate Z thatit produces suiiicient friction thereon to retain it in any-position to which it may be turned, and thus retain the tension of the spring.

p p are two binding-screws screwed-into the stand C, 'and having soldered to each of them one of the two ends of the wire forming the helicesot the electro-magnet. q q are two other binding-screws, screwed into the edge otthe stand Ato connect the-wires of the telegraphline, said screws being connected 'with p p by wires rr.

I is a tube, of brass or other metal, made with an elbow, passing through holes in the stands A C and india-rubber'B, and iirmly secured to the standA by a -metal stra-p, s, or by any other suitable means. The hole provided in the india-rubber B for the tube [to pass through is smaller than the tube before the insertion of the latter, for the purpose 'of preventing the ingress or egress of air through the stand C. The-portion of the tube I above the stand O is upright, and has-fitted tightly into it the lower end of the upright portion of a tube, J, which is also of elbow form. The horizontal portion of this tube stands over the space 'between the two helices of the electro-magnet and parallel with the axes of saidheIiceS, and it is made with a slot, t, in its under side and a screw-thread, u, upon its exterior, both commencin g at its mouth and extending back some distance therefrom, the said slot being for the reception 'of t-he hammer-like head c of the armature-lever F,vwhich is free to oscillate'within it without tou'chingits sides, and the screwthread being for the reception of two internally-screwed collarsfw w', which are placed on the exterior of the tube, one in frontand the other behind the lever. These collars serve to limit the oscillating movement of the lever produced by opening and closing the circuit in which the magnet is placed, and it is by the hammer-like head of the armature-lever striking against-these collars that the sounds by which the message is tobe read are produced.

K is aexible tube, of india-rubber or other material, attached at one end to the'portion of the tube I that is outside of the stand A, and

furnished at the other end with an ear-piece, L, of hard india-rubber or other material. This ear-piece is represented as of suitable form to tit the side and top ofthe head in such manner as to beV secured inplace by a hat or cap worn by the operator, as shown in Fig. 1. The tubes I J K combined constitute theacoustic tube, whose combination with 'the magnet or other sounding device is the principalteatnre ot my invention.

M',Fig.'1, is the cover inclosing the magnet,'

the armature-lever, and the tube I, for the purpose of preventing as far as practicable the escape ot' sound otherwisethan by the acoustic tube. This cover may be of various materials and variously-applied; but the'simplest and most convenient thing that can be used is the glass shade represented.. The lower edges of this shade iit within the rim a of the stand -to strike the inner collar, fw, of the tubeJ, and

when the circuit is ,opened the spring draws the lever back and causes it to strike the outer collar, w', and so produce a'fseries, of clicking sounds, and the different lengths of time which the currents are allowed to flow determines the signs. When the Bow is but for an instant it .may be represented in an alphabet by a dot,

(,) and when for a little longertime-say a quarter of a second-by a dash',l(,,)and an alphabet may be formed by suitable combinations ot these signs. The alphabet in most common use or any other may be used; but I propose to use that represented in Fig. 4 of the drawing.

The adjustment of the collars to 'w' may be such that the sound produced by the lever striking them will be so feeble that it cannot be heard by a person very near the instrument, even with the cover M removed, and yet will be heard .by the operator with the acoustic tube applied to his ear. Whenl the cover is applied and the communication prevented between the air immediately surrounding the instrument and the air outside ofthe cover, the adjustment is not required to be so delicate,

yas the sound will be shut in from bystanders and all conveyed into the tube.a

Instead of using a tube to convey the sound to the ear, the instument may be placed in a boxv .of convenient height, with an orifice,

against which the operator may place his ear' and hear almost, it' not quite, as well as through v atube. Such a box I consider the equivalent of the acoustic tube.

I do not confine myself to the use of any particular instrument or devicfcr obtaining the sounds which are to constitute or denote the signs or signals employed; but

What I claim as my invention, and desire to secure 4by Letters Patent,.is` v 1. The employment f an acoustic tube or its equivalent, combined with the armature lever of an electro-magnet, or with any equiv- 3. The employment of a cover iuclosiu g the aient instrument for producing sounds by elecinstrument for producing the sounds and the tricity, to operate substantially as and for the mouth of the acoustic tube, substantially as purpose herein set forth. and for the purpose herein specified.

2. The employment as stops for the arma- T T ture-lever or other device by Whose movement ALEXAD DER BAD the sound is produced, of collars or their equiv: Witnesses alents zo 1v', adjustable upon the acoustic tube M. M. LIVINGSTON,

itself, substantially as herein specified. JAMES LAIRD. 

